Consider a system where processes frequently block on I/O, causing many context switches. How does this behavior affect CPU utilization and why?

medium🧠🧾 Concept Trace Q4 of Q15

Operating Systems - Context Switch - Cost & Causes

ACPU utilization increases because blocking processes free the CPU for others to run.

BCPU utilization increases because the CPU spends more time saving and restoring registers.

CCPU utilization remains unchanged because context switches do not affect CPU time.

DCPU utilization decreases because frequent context switches add overhead and reduce time spent executing processes.

Step-by-Step Solution

Solution:

Step 1: Understand impact of frequent blocking
Frequent blocking causes many context switches, which add overhead and reduce effective CPU time for useful work.
Step 2: Analyze options
CPU utilization does not increase because overhead reduces effective CPU time. It does not remain unchanged because context switches consume CPU cycles. CPU utilization does not increase due to saving/restoring registers; this is overhead, not productive work.
Final Answer:
Option D -> Option D
Quick Check:
More context switches -> more overhead -> less CPU for processes [OK]

Quick Trick: More context switches reduce CPU time for actual processing [OK]

Common Mistakes:

MISTAKES

Trap Explanation:

PITFALL

Candidates often think blocking frees CPU and increases utilization, ignoring overhead cost.

Interviewer Note:

CONTEXT

Master "Context Switch - Cost & Causes" in Operating Systems

2 interactive learning modes - each teaches the same concept differently

Want More Practice?

15+ quiz questions · All difficulty levels · Free

More Operating Systems Quizzes